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The AT4, is a new, off-road-oriented model for the wide-ranging 2019 Sierra lineup. (GMC)

With 2019 Sierra, GMC puts brand differentiation behind it—literally

2018-10-03
Bill VIsnic

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That the all-new 2019 GMC Sierra 1500 pickup uses GM’s same T1 fullsize-truck architecture as the 2019 Chevrolet Silverado was of course preordained. The new platform comes with a raft of design and engineering tricks that mostly targeted weight reduction and increased structural integrity and refinement via sophisticated mixed-metals applications (https://www.sae.org/news/2018/04/truck-tech-war).

Mostly employing the same mechanicals as the Chevrolet Silverado, the job for the GMC brand typically is delivering an appropriate degree of differentiation from its high-volume Chevy counterpart. That’s been executed with any number of strategies over the long pickup-truck history of both marques, but the 2019 Sierra does so with maybe the most interesting ammunition yet—and almost all of it located at the back: a carbon-fiber reinforced plastic (CFRP) cargo box and a clever reconfigurable tailgate

Weight-chopped box

The CFRP cargo box accounts for 62 lb (28 kg) of the Sierra’s curb weight reduction that totals as much as 360 lb (163 kg), including 88 lb (40 kg) chopped from the T1’s fully-boxed frame. The company also claims best-in-class resistance to just about every destructive thing that can happen to a pickup box, thanks to the CRFP material supplied by Japan’s Teijin; the company’s Continental Structural Plastics plant that makes the CRFP “inner” is located near the Sierra’s assembly plant in Fort Wayne, Indiana.

Teijin recently broke ground for a carbon-fiber production plant in Greenwood, South Carolina, as the cornerstone of a push to cut the cost of the material and drive wider use in the auto and aerospace sectors.

“A lot of the intellectual property comes from the way we manufacture it,” Tim Herrick, executive chief engineer for GM’s fullsize pickups, told Automotive Engineering at the media launch for the Sierra Denali and AT4, the first models to hit showrooms; the buying the top-of-the-line Denali, by the by, will be the only way to get the carbon-fiber box, for now exclusive to GMC. Constructed on for the short-bed configuration of Denali, the 5-ft 9-in short box is 1 in (25 mm) longer and 2 in (50 mm) taller than that of the previous generation Sierra.

Another advantage, said Herrick, is that the carbon-fiber material box also boasts 1 cu ft more cargo space because its sidewalls are thinner. This in addition to the 7 in (178 mm) wider all boxes already are for the Sierra line.

Herrick would not say how much GM plans to charge for the optional box, but he and other engineers seem to expect the availability will expand to other models, suggesting the price will not be outlandish.

The rollout scheme does recall, however, a previous GM attempt in the early 2000s to market a fully composite bed—dubbed Pro-Tec—for fullsize Chevy and GMC pickups. Sales were dismal because, among other factors, Pro-Tec’s price was a fraction of the cost to install an optional plastic bedliner that delivered most of the same advantages and typically netted more profit for dealers.

For the new CarbonPro Box, Herrick said the carbon material goes into the tool “almost like an origami, all folded up,” and then is heated to form the net shape. Apart from the material itself, the CarbonPro Box installs on the assembly line essentially in the same fashion as the standard box, he added.

Gate-a-palooza

The Sierra’s back-loaded story doesn’t end with the CarbonPro cargo box. Access to it and the standard steel boxes on the Sierra Denali, AT4 and SLT trims comes via the new MultiPro tailgate, a split-gate design that provides six different configurations intended to facilitate access to the bed, provide a full-width step into the bed and serve essentially as a built-in bed extender or “load stop” to secure long, flat items.

Our favorite configuration, however, proved to be the one that allows the upper portion of the gate to be partially folded to create a comfortable standing-height work surface. The MultiPro gate, another feature for now exclusive to GMC, is too useful to not proliferate and it’s widely expected the multi-configuration gate soon will extend to other models.

Engine extravaganza

The passenger-vehicle world may be converging on 2 liters, but don’t expect the pickup market to follow. The 2019 Sierra lineup is available with no less than six engine-transmission combos. At the launch, buyers will have the choice of 5.3-L and 6.2-L V8s enhanced by Dynamic Fuel Management cylinder deactivation to improve fuel economy (https://www.sae.org/news/2018/05/gm-2019-v8s-with-dfm-system); DFM—now using 17 programming maps to determine which of any of the cylinders can be deactivated—is a further improvement of GM’s longstanding Active Fuel Management system.

Jordan Lee, chief engineer for GM’s small-block engines, earlier this year said equipping the 5.3-L and 6.2-L V8s was “equivalent to making an all-new engine.” The 5.3-L is backed by an 8-speed automatic transmission, while the 6.2-L uses GM’s newer 10-speed automatic; four-wheel-drive versions of the Sierra with the 3550hp 5.3-L are rated at 15 mpg city/21 mpg highway and 4WD models with 420-hp 6.2-L are good for 15/20 ratings.

Other Sierras in the model range can be fitted with a base 4.3-L V6 (285 hp); the new (and first-ever for a GM fullsizer) turbocharged 2.7-L I-4 (310 hp); an AFM-fitted version of the 5.3-L V8 with a 6-speed automatic and a totally new 3.0-L inline six-cylinder turbodiesel, for which GM has yet to provide detail and, like the 2.7-L 4-cylinder, is a later addition to the 2019 Sierra line.